Certain alien-addition lines of Aegilops squarrosa in durum
wheats have been used to study the association of certain
characteristics with different D-genome chromosomes (Alston 1970;
Makino 1981). However, in those attempts, it was not possible to
recover and unequivocally identify the seven D-genome addition lines.
Moreover, the available D-genome chromosome addition lines were
developed in mixed backgrounds involving several durum parents.
Dhaliwal et al (1990) for the first time developed a complete set of
D-genome monosomic addition lines of Aegilops squarrosa (DD)
accession 3754 in T. durum Desf. cv. PBW-114 using Giemsa
C-banding. Four monosomic addition lines were for normal chromosomes
1D, 2D, 3D and 6D while the remaining three chromosomes 4D, 5D and 7D
were represented by translocated chromosomes 4DS-5DS, 7DS-5DL and
7DL-4DL.

All the seven monosomic addition lines of Ae. squarrosa in
durum background PBW-114 were planted at the Punjab Agricultural
University, Regional Research Station, Gurdaspur, Punjab, India in
winter 1989-90 for the investigation of association of various traits
with individual D-genome chromosome. Monosomic addition plants for
each of the addition lines were identified through cytological
analysis and association of morphological characters (Dhaliwal et al
1990). Disease severity and other traits was recorded on five
monosomic addition plants of the seven monosomic addition lines.

Monosomic addition lines 2D and 7DS-5DL possessed gene(s) for leaf
rust and stripe rust susceptibility, respectively (Table
1). Monosomic
addition lines 3D and 6D were completely free from Karnal bunt,
showing that these chromosomes carried epistatic gene(s) for Karnal
bunt resistance. Gill et al (1987) also reported genes for Karnal
bunt resistance on 3D and 6D chromosomes of T. aestivum by
using ditelosomic series of T.aestivum cv. Chinese
Spring. Chromosome 2D addition line had vitreous grains while all
other lines and the durun parent had grains with yellow berry.
Therefore, chromosome 2D, of Ae. squarrosa, possesses gene(s)
for grain vitreousness. Gene(s) for round-shaped grain were present
on chromosome 6D. Gene(s) for small grain size seemed to be located
on chromosomes 1D and 3D as revealed by data on 1000-grain weight.
Line 3D had the narrow leaves as compared to other addition lines.
Makino (1981) also had reported genes for narrow leaves on chromosome
3D of Ae. squarrosa.

By using these seven monosomic addition lines Dhaliwal et al
(1990) had reported the association of gene(s) for non-waxy character
on chromosome 2D, lax head shape on chromosomes 2D, 7DS-5DL and
4DL-7DL, gene(s) for red glume colour on chromosome 1D, and red seed
colour on chromosome 3D. The knowledge of association of gene(s)
controlling disease resistance, seed characteristics, yield
components and morphological traits with various Ae. squarrosa
chromosomes can be used to identify the monosomic addition lines
without resorting to cytological analysis, explore Ae. squarrosa
germplasm for variability for the traits and breed durum and
bread wheats using squarrosa lines with requisite
variability.